An alkaloid aricine (C20 H12 No3 ?) was found by Pelletier in arica; it has not, however, been rediscovered, and some doubts exist with regard to it. It is stated to crystallize in needles, to be soluble in ether, and give an intense green colour with nitric acid. Guibourt has obtained cinchonia, not aricina, from the same bark.

The substance known by the name of quinoidine consists of resinous and colouring matters, with the above alkaloids more or less changed by the processes to which they have been subjected; it is obtained from the liquors from which the sulphate of quina has been crystallized; it was from this substance that Liebig obtained his amorphous quinine, which bears the same relation to the crystallized alkaloid as uncrystallizable syrup does to ordinary sugar; probably it is closely allied to quinicine.

The salts of the cinchona alkaloids commonly used in medicine are as follows: -

Quinae Sulphas. Sulphate of Quinia (C40 H24 N2 O4, HO, So3 + 7 HO), it occurs in snow-white feathery crystals, requiring for solution about 60 parts of strong spirit, and 750 parts of water; and the watery solution, treated with chlorine, and ammonia, gives the green test before noticed, and also exhibits fluorescence; it has all the characters of a neutral salt. For the adulterations, etc, of sulphate of quinia, see page 261.

Prep. The following are the directions given for the preparation of the sulphate in the British Pharmacopoeia: "Take of yellow cinchona bark, in coarse powder, one pound; hydrochloric acid, three fluid ounces; distilled water, a sufficiency; solution of soda, four pints; dilute sulphuric acid, a sufficiency. Dilute the hydrochloric acid with ten pints of the water. Place the cinchona bark in a porcelain basin, and add to it as much of the dilute sulphuric acid as will render it thoroughly moist. After maceration, with occasional stirring for twenty-four hours, place the bark in a displacement apparatus, and percolate with the diluted hydrochloric acid, until the solution which drops through is nearly destitute of a bitter taste. Into this liquid pour the solution of soda, agitate well, let the precipitate completely subside, decant the supernatant fluid, collect the precipitate on a filter, and wash it with cold distilled water, until the washings cease to have colour. Transfer the precipitate to a porcelain dish containing a pint of distilled water, and applying to this a steam heat, gradually add dilute sulphuric acid until very nearly the whole of the precipitate has been dissolved, and a neutral liquid has been obtained. Filter the solution while hot through paper, wash the filter with boiling distilled water, concentrate till a film forms on the surface of the solution, and set it aside to crystallize. The crystals should be dried on filtering paper without the application of heat."

["Take of yellow cinchona, in coarse powder, forty-eight troy ounces; muriatic acid, three troy ounces and a half; lime, in fine powder, five troy ounces; animal charcoal, in fine powder, sulphuric acid, alcohol, water, distilled water, each, a sufficient quantity. Boil the cinchona in thirteen pints of water, mixed with one-third of the muriatic acid, and strain, through muslin. Boil the residue twice successively with the same quantity of water and acid as before, and strain, mix the decoctions, and, while the liquid is hot, gradually add the lime, previously mixed with two pints of water, stirring constantly, until the quinia is completely precipitated. Wash the precipitate with distilled water, and, having pressed, dried, and powdered it, digest it with boiling alcohol. Pour off the liquid, and repeat the digestion several times until the alcohol is no longer rendered bitter. Mix the liquids, and distil off the alcohol until a brown viscid mass remains. Upon this, transferred to a suitable vessel, pour four pints of distilled water, and, having heated the mixture to the boiling point, add as much sulphuric acid as may be necessary to dissolve the quinia. Then add a troy ounce and a half of animal charcoal, boil the liquid for two minutes, filter while hot, and set it aside to crystallize. Should the liquid, before filtration, be entirely neutral, acidulate it very slightly with sulphuric acid. Should it, on the contrary, change the colour of litmus paper to a bright red, add more animal charcoal. Separate the crystals from the liquid, dissolve them in boiling distilled water slightly acidulated with sulphuric acid, add a little animal charcoal, filter the solution, and set aside to crystallize. Lastly, dry the crystals on bibulous paper, with a gentle heat, and keep them in a well stopped bottle. The mother water may be made to yield an additional quantity of sulphate of quiniae by precipitating the quinia with water of ammonia, and treating the precipitated alkaloid with distilled water, sulphuric acid, and animal charcoal as before." U. S.]

Cinchoniae Sulphas, or Sulphate of Cinchonia (C40H24N2O2, HO, So3 + 2 HO), occurs in prisms, often of considerable size, requiring for solution about 6 parts of strong spirit and 54 parts of water: the solution is not fluorescent, and does not give the test with chlorine and ammonia.

Quinidinae Sulphas, or Sulphate of Quinidine (C40H24N2O4, HO, So3 + 6 HO), in acicular shining crystals, requiring 2 parts of spirit and 130 parts of water for solution; the solution is fluorescent, and gives the green colour with chlorine and ammonia.

Cinchonidinae Sulphas. Sulphate of cinchonidine (C40 H24 N2 O2HO, So3 crystallizes in stellate groups of silky needles, soluble in water; the solution is fluorescent, but does not give the green colour when treated with chlorine and ammonia.

Besides the above salts, Valerianate of Quina (described under Valerian), Citrate of Iron and Quinine (described under Iron Salts), and Arseniate of Quinine are occasionally employed in medicine, but their special value is somewhat doubtful. The cinchona alkaloids also form with acids salts which are acid in reaction, and when the ordinary sulphates are administered, dissolved in excess of acid, as they usually are, such salts are produced.